William Blair Mid Cap Growth Fund: An Anniversary Worth Celebrating
The William Blair Mid Cap Growth Fund achieved an important milestone on February 1, 2009, as the date marked the three-year anniversary of the Fund. Here's why it's an anniversary worth celebrating: Morningstar has awarded the Fund an Overall and Three-year rating of five stars for the period ending 3/31/09. (Class I Shares) The Fund is ranked among top-performing mid cap growth funds for one year performance ending 3/31/09 in the Wall Street Journal. (Class I Shares) We invite you to find more about the William Blair Mid Cap Growth Fund by using any of the quick links to the right.	Mid Cap Growth Fund Quick Links: Fact Sheet Commentary Quarterly Review Prospectus
Morningstar Ratings™ are as of 3/31/2009 and are subject to change every month. The ratings are based on a risk-adjusted return measure that accounts for variation in a fund's monthly performance, placing more emphasis on downward variations and rewarding consistent performance. The top 10% of funds in each Category receive 5 stars, the next 22.5% receive 4 stars, the middle 35% receive 3 stars, the next 22.5% receive 2 stars, and the bottom 10% receive 1 star. The Overall Morningstar Rating for a fund is derived from a weighted average of the performance figures associated with its three-, five-, and ten-year (if applicable) Morningstar Rating metrics. Investing in smaller and medium capitalization companies involves special risks, including higher volatility and lower liquidity. Mid cap stocks are also sensitive to purchase/sale transactions and changes in the issuer's financial condition. The William Blair Mid Cap Growth Fund – Class I Shares was ranked 10th out of 564 Funds based on one-year total return for the period ended 3/31/09 in the Mid-Cap Growth Fund category by Lipper, a Reuters Company. For the three-year period, the Fund's rank was 39 out of 488 Funds. The Fund has not been in existence long enough to earn a ranking for 5 years.